Then someone told David, saying, "Ahithophel is among the conspirators with Absalom." And David said, "O LORD, I pray, turn the counsel of Ahithophel into foolishness!"
2 Samuel 15:31
Surrounding context
15:30 So David went up by the Ascent of the Mount of Olives, and wept as he went up; and he had his head covered and went barefoot. And all the people who were with him covered their heads and went up, weeping as they went up.
15:31 Then someone told David, saying, "Ahithophel is among the conspirators with Absalom." And David said, "O LORD, I pray, turn the counsel of Ahithophel into foolishness!"
15:32 Now it happened when David had come to the top of the mountain, where he worshiped God--there was Hushai the Archite coming to meet him with his robe torn and dust on his head.